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Cod
The''' Cod''' (Gadus morhua) is a very well known British saltwater fish. 'Identification' Classic codfish shape, with three rounded dorsal and two anal fins. The pelvic fins are small with the first ray extended, and are set under the gill cover (ie the throat region), in front of the pectorals. The upper jaw extends over the lower jaw, which has a well developed chin barbel. Medium sized eyes, approximately the same as the length of the chin barbel. Distinct white lateral line running from the gill slit above the pectoral fin, to the base of the caudal or tail fin. The back tends to be a greenish to sandy brown, and showing extensive mottling especially towards the lighter sides and white belly. Dark brown colouration of the back and sides is not uncommon especially for individuals who have resided in rocky inshore regions. 'Breeding' The Cod population comprises of a number of reasonably distinct stocks over it's range. These include the Arcto-Norwegian, North Sea, Faroe, Iceland, East Greenland, West Greenland, Newfoundland, and Labrador stocks. There would seem to be little interchange between the stocks, although migrations to their individual breeding grounds may involve distances of 200 miles or more. Spawning occurs between January to April (March to April, is the peak time), at a depth of 200m in specific spawning grounds at water temperatures of between 4-6oC. Around the UK, the major ones are associated with the Middle to Southern North Sea, the start of the Bristol Channel (north of Newquay), The Irish Channel (both east and west of the Isle of Man), around Stornoway, and east of Helmsdale. Pre-spawning courtship involves fin displays, and male grunting, which leads to pairing. The male is inverted underneath the female, whilst the pair swim in circles during the spawning process. The eggs are planktonic and hatch between 8 to 23 days with the larva being some 4mm in length.This planktonic phase lasts some ten weeks, during which the young cod will increase it's body weight by 40 times, and be about 2cm in length. The young cod move to the seabed and their diet changes to small benthic crustaceans, such as isopods and small crabs. They increase in size to 8cm in the first six months, 14 to 18cm by the end of their first year, and some 25 to 35cm by the end of the second. This rate of growth tends to be less in individuals occupying northerly grounds.Cod reach maturity at about 50cm in length at about 3 to 4 years of age.Gadus 'Habitat' Varied, although often favouring rough ground especially inshore. Demersal in depths of between 20 to 200m (80m Av.), although not uncommon to depths of 600m. Gregarious and forms schools, although shoaling tends to be a feature of the spawning season. 'Food' Adult cod are active hunters, feeding on sandeels, whiting, haddock, small cod, and squid, with a variety of benthic annelids, crustacea, and molluscs supplementing their diets. 'Range' Throughout most of the UK waters, although generally seen as a winter fish in the south. 'Additional Notes' Major commercial fish, although stocks have been damaged in the past through over fishing. Good eating. Gallery Baby Cod Lochaline.jpg|Baby Cod - Dave Park Cod.jpg|Adult Cod - Dave Park References Aquarium Project - Page : http://web.ukonline.co.uk/aquarium/pages/cod.html Category:Fish Category:Saltwater Fish Category:Chordata Category:Vertebrates